(a) Technical Field
The present invention relates to a combined control apparatus and method for a lamp of a vehicle. More particularly, the present invention relates to a combined control apparatus and method for a lamp of a vehicle, which enables turn-on control of a lamp by using a switch direct drive method together with a Micro Control Unit (MCU) control method.
(b) Background Art
Generally, lamps for vehicles include stop lamps (e.g., brake lamps) for warning following other vehicles that the vehicle is breaking, in addition to head lamps and turn signal lamps. Once a vehicle begins braking initially, the brake lamps must be quickly turned on in order to notify vehicles behind the vehicle that that vehicle is braking to prevent the subsequent vehicle from running into the back of that vehicle.
Typically, however, a certain amount of time is taken for the brake lamp to be lit, i.e., a turn-on time from the moment that the braking starts to the moment that the stop lamp is turned on, and thus this time period needs to be minimized. Typical control methods for turning on a stop lamp of a vehicle are divided into a switch direct driving method (non-MCU control method) and a Micro Control Unit (MCU) control method.
In the switch direct driving method, when a driver steps on a brake pedal, a switch is turned on to apply a current signal to an Intelligent Power Switching (IPS) device (e.g., a semiconductor device) connected to light a bulb within the brake lamp. The brake lamp is then lit by a power switching operation of the IPS device. In the switch direct driving method, turning on the brake lamp takes only about 5 ms from the moment the switch is turned on to the moment the bulb of the lamp is lit, therefore a following vehicle can quickly identify when the vehicle ahead of it is braking.
However, since the switch direct driving method directly lights the stop lamp without a Pulse Width Modulation (PWM) control (i.e., which is found in the MCU control method), diagnosing whether the bulb is operating appropriately through the system is impossible. In addition, the lifespan of the bulb may also be shortened.
In the MCU control method, a switch is turned on when a driver steps on a brake pedal. This inputs a switching-on signal from the switch into an MCU. The MCU then performs its own operation process and applies a current from the MCU to an IPS device. The bulb of a brake lamp it then lit by a power switching operation of the IPS device.
For example, Japanese Patent Application Publication No. 2004-355887 discloses a lamp control method in which a lamp is controlled with a low duty ratio when the lamp is initially lit and the duty ratio is gradually increased from there. Also, Japanese Patent Application Publication No. 2011-225055 discloses a control method in which judgment logic is executed to light the brake lamp when a driver steps on a brake pedal.
However, since the lamp lighting process by the MCU control takes substantially more time than the switching direct method to execute each lamps judgment logic, it takes about 40 ms to light the bulb in the brake light from the time the switch is turned on to the time the bulb is lit. The MCU control method is substantially slower.
Thus, in the switch direct driving method, since the turn-on time is only about 5 ms, following vehicles can quickly identify that the preceding vehicle is braking. However, in the MCU control method, since it takes about 40 ms to turn on the brake lamp, following vehicles may, in some instances, be notified two late that the preceding vehicle is braking, thus, causing an accident.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.